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JH.

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_________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

For (more or less) realistic emulations of string instruments (like in th esecond part of this sample: http://jhaible.heim.at/string_filter/jh_string_filter_benadecello_cs50.mp3 ), you need the 40-band filter plus a few broader resonances that I have created with a 3-band parametric EQ for each of the thre "presets", violin, viola and cello. (Thats the big veroboards with loads of trimpots).

Now, I expect much bigger interest in the 40-band filter than in the preset section, so I think I'll offer the 40-band filter PCBs separately. (Actually, these will be two equal boards for 20 bands each.)

I'm still looking for the best solution of the Para EQ stuff.
Maybe I'll make it part of the "Famous Fixed Filters" project.
Maybe I'll recommend using the Moog Parametric EQ board for this.
Maybe most buyers of the 40-band Filterbank have enough means for parametric EQ-ing already, and don't need a dedicated board for this at all.
I'll try to find out.

Meanwhile, I concentrate on the heart of it, the 40-band Filter Bank.
Back then, I used a design I thought clever - only to find out that it only was stable with NE5532 chips of a specific date code. That's why I didn't publish the old PCB layouts in the first place.
Now, I go for a different circuit topology, that also has a lot of benefits over the typical single-opamp solutions.
These will be 2-opamp biquads, which utilize a negative resistance to create a non-inverting integrator. (Also known as Deboo-integrator).
The main benefit of this - apart from it's low noise - is the low reistor spread, and zero capacitor spread. Which means, you need a lot of ...

Quote:

Any special parts one might start sourcing for the future?

... 10k resistors!

Yes, you need about 160 of these.
The layout will be such that you can either use ordinary resistors, vertically mounted, or 8-pin SIL resistor arrays. (You can see these components - in red - in th eold version, too.)

Quote:

Don't worry, no obligation implied).

I'm pretty sure that I'll make this available, if these is enough demand.

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Now, I expect much bigger interest in the 40-band filter than in the preset section, so I think I'll offer the 40-band filter PCBs separately. (Actually, these will be two equal boards for 20 bands each.)

I'm still looking for the best solution of the Para EQ stuff.
Maybe I'll make it part of the "Famous Fixed Filters" project.

I for one would be interested in the presets. If the "FFF" would do the job, two birds with one stone.

_________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

....you need the 40-band filter plus a few broader resonances that I have created with a 3-band parametric EQ for each of the thre "presets", violin, viola and cello. (Thats the big veroboards with loads of trimpots).

....I'm still looking for the best solution of the Para EQ stuff.
Maybe I'll make it part of the "Famous Fixed Filters" project.

From an FFF perspective, this sounds ideal. Even if not used with the String Filter, it would still provide a decent processing facility.

I feel like I'm the only one still jazzed about the whole FFF idea.... That thread has become such a lonely place....

I wish you could make the boards in the US, They would cost you much , much less to make. they could be legended in uf and pf so I don't have to keep a conversion chart on hand, The way things are going US customers are being priced out of the market. The price increases on some things have gotten up to %300. it is not just the exchange rate, it is the way we are taxed in the US. We are taxed up front with small sales taxes as an additional penalty., No VAT or anything like that, we would be better off paying vat.

For many years I pressed my records in Holland and shipped them back to me in the US. for quality and price reasons.

Right now a set of Klee boards cost 18 Euros converted from $28 for a pair and they are not small boards. I can buy all of these I want but I can't do the same for stuff made in UK and Europe.

At that cost differential what am I going to be forced to choose a Mankato or a Journeyman. It is not the Americans comeuppance, it will be the forced rollback of trade. These conditions killed the Mellotron back in the 80's. The imbalance is bad for anybody selling from europe right now.

I'm not happy about the Dollar - Euro exchange rate, either.
It *is* a problem for many German companies that are living from export, indeed.
But we're living in the Euro zone, we have to buy our clothes and feed out children with Euros, so we have to find a means to make up for this unfortunate exchange rate.
My way to tackle the problem is to try and give you the best value for your money by the way I design my boards. If you look at the Triple Chorus board, for example, and compare it with the boards inside a vintage Crumar performer, you'll see that the Crumar uses 4 or 5 times the PCB space that I need for the same function. (Estimated - not measured.)
Believe me, I could layout the circuit on a board with the Crumar form factor (actually: 5 separate boards there!) in a couple of hours.
The way I have done it, it takes several days, and I had to find a clever way to prevent the BBD lines from interlocking.
That's both, hard work, and also lot of fun (because I like the challenge), and it gives you a board that is affordable (because it's now in a much smaller size), despite the unfavorable Dollar exchange rate.

And of course you can buy other products instead of mine. We're not enemies here, and I enjoy the good feelings we hobby and part-time-business DIY'ers have towards each other. Personally I try to focus on projects that are not already covered by others (see the recent Dimension D discussion), so I hope I can continue offering PCBs that are interesting and find buyers that consider them a good value for their money.

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

The VC resonance will need a transistor pair like the LM394 or SSM2210 or MAT-02, or a selected pair of cheap NPN tansistors.
That's part of the whole concept, and therefore required.

The Limiter will need a Vactrol. I have yet do find out which type will work best, and the circuit can be adapted to use different types, too. It's a rather simple limiter - just to prevent harsh sounds from overdriving.
The Limiter is optional - you can simply omit the Vactrol and a handfull of passive components if you don't need it.

The Body, bridge and Air resonances for emulating "real" string instruments are not part of this 2-board project. That will be a different project alltogether, and will be handled separately in the future.

Each of the 40 resonators also has an individual output where you can connect whatever you want. If you like extemes, you can connect 40 slider potentiometers here and control each band separately.
If you want to do this, you have to wire the required passive components separately, though. (like, coupling capacitors to prevent DC on the potentiometers, summing resistors, and so on.) My boards will provide rudimentary means to go into that direction, i.e. it makes such a modification easier; but it will still be a modification, and not for the faint of heart.

All in all I'm getting along fine with this project - I'll even be able to include PSU electronics with heatsinks on one of the 160mm * 100mm boards. Unlike the Krautrock phaser, you'll have to wire the fuses off-board this time, however.

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Now playing: Pink Floyd, Ummagumma_________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Now playing: Tori Amos, From The Choirgirl Hotel_________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

The new filter topology works great!
And trimming these filters works like a charm.
They are stable, with TL072 chips.
You can use 10% capacitors here, and still you have almost one turn of the multiturn trimmers to walk along the peak of the BPF transfer function.

Still have to build the VC resonance and the Stereo Spread function, and the on-board PSU. If this works, I'll order a second board to build a complete 40-band prototype.

JH.

Now Playing: Mike Oldfield, Ommadawn_________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Quick demo, as long as the computer works.
(Yes, all paid orders are packed now, too. That was my main focus today.)

This is one half of the proposed 40-band filter bank only: 20 bands.

You hear a mix of noise and a sub-audio square wave from the Synthi Clone processed with the filter bank, and resonance gradually increased.
There is no reverb in this demo - it's all from the filters.

(Yes, there's a nasty ground loop in the audio - I quickly patched the prototype across half the room with an unbalanced connection.)

_________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Thanks for the sample--that's great! It really does sound like reverb or room ambience. Seems to me this filter will have a vast range of uses. Looking forward to it! BTW, I didn't hear any ground noise, even on headphones.

Now playing: Vangelis, Chariots of Fire_________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

The extra equalisation will be available later, on a separate board (Board 3).

I'll keep this separate, because I expect more interest in Board 1 and 2 than in Board 3, so maybe I'll combine Board 3 with something else, like a vocal filter (VP330 human voice maybe - this will be decided later.)

I think it's also possible to do the extra equalization with outboard equipment (parametric equalizers) - the filter bank is the tricky part, and that's what you buy with Board 1 and Board 2.

Right now, I'm taking pre-orders for Board 1 and Board 2 only.
I'll wait a couple of weeks before I put my order to the PCB house. It will probably take a couple of months before the PCBs are ready for shipping. But I need binding pre-orders now, to calculate if the project makes sense at all. You don't have to pay anything now - I'll only send invoices when I actually have the boards ready for shipping.

I'm only selling the printed circuit boards (PCBs) for this. You have to buy all the necessary components yourself.
I'll provide information how I've built my own string filter, using these PCBs (schematics, component overlay, BOM, etc.).
And I'll answer questions about it in this forum:
http://electro-music.com/forum/topic-20360.html

(I've you've sent me a mail before, showing interest in this project, please send an official order mail as described below, nevertheless.)

If you're interested, please send the following order form including the email subject line (important!), with the quantity you want filled in:
(just copy and paste the text, and fill in your personal data.)

and don't forget the email subject line with the number of PCB *sets* (1 Set = 2 boards = EUR 54.00)

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

I've skimmed over this thread and I must say that this string filter thingie is just about the best thing since sliced bread! The audio sample was very convincing as are the comments and order requests of others.

I would like to make a simple version of it in ChucK as part of my guitar effects processing software, just to see how it sounds. I'm thinking that for a guitar I'd only need about 10 or 20 filters ranging from 80 Hz to 1.5 kHz. I'd use ChucK's BPF (band pass filter) model and put them all in parallel, neglect the additional instrument-simulating filters, and set the Q of each filter. Is that correct? If so, at what frequencies would I place the filters? Are they spaced logarithmically in frequency as you'd expect? If so, could I put them at 80 Hz, 160 Hz, 320 Hz, and so on? Also, what value of Q should I set the filters for? Oh, and more importantly, do you think the filter would be any good as a guitar effect? The guitar is already a string instrument but this filter might add sustain to each note for example.

Sorry if I should have learned the above from the web page or the thread. This thing is so cool that it must be ChucKed!_________________"Let's make noise for peace." - Kijjaz

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

I'll publish the relevant data as the project proceeds.
I won't give anything away beforehand, though.
Let the analogue come first, and then make a VA version!

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

could you estimate how much the costs for all the parts are ?
maybe you could also name me a company where i can order them.

I haven't started with a BOM yet.

But I'll give you a rough overview:

You need 40 multiturn trimpots, 40 TL072 chips and 80 capacitors (10% tolerance or better) for the filter bank. Plus some extra opamps and one LM394 or similar dual transitor for the VC resonance, stereo spread, etc.
Plus a multitude of resistors and 100nF bypass capacitors.
Resistors: I recommend using 8-pin SIL arrays with four 10k resistors each; you need 40 of these. Alternatively, you can use 160 vertically mounted 1% metal film resistors of 10k.
If you want an optoelectronic limiter function, you need a VTL5C3 Vactrol.
(This is optional.)

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Okdokey, I just sent you an email. It will be 2 sets for me. And I´m looking forward to seeing what will be on PCB 3. _________________A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"

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